This week, for the magazine — the "mag" in that "nymag.com" address you see above — we wrote about the next frontier in advanced baseball analysis: quantifying defense. Why did the Yankees not pay up for Matt Holliday or Jason Bay? Why did the Red Sox want everyone to get so excited about Mike Cameron? Why did the Mets ... well, why do the Mets do anything? Many of the big decisions teams are making today are based on new defensive metrics that are confusing and unproven, but vitally important. And hey, look: Jeter's good at defense in these metrics! (Well, for now.) Come, watch us attempt to take hard math problems and turn them into lifestyle-magazine prose!